Firstly, thanks for the great mag.
Secondly on page 33 of issue 33 Richard Smedly
goes into detail about octal numbering relating to
file permissions without first stating what he is referring too.

Had to look up external references to see what was going on.
Apparently its got to do with changing ownership using those octal
numbers. This is done by using chmod XXX filename where XXX refer
to the octal numbers spoken about in the article.

Although I am very familiar with binary, octal and pretty much any other number base used in computing, I just use this basic method for working out permissions (ok, it is pretty much what you said, but worded differently).

As you said, there are three groups of permissions. Each group can contain "r" for Read access, "w" for Write access and "x" for execute file or list directory contents access.

I just remember that r=4, w=2 and x=1 (yes, that's binary, but you don't need to know that to start with).

I have a problem seeing the text in some of the callout boxes on the .pdf version of issue 39.
The boxes pointing to items in the illustrations on pages 32,34,37, 39, and 58 are black. It looks like the the text might be behind the black boxes.
The text boxes on page 36 look correct.

I'm using Windows 8.1 and the built-in reader program from Microsoft. (Hopefully I won't be banished for that.)

Thank you. You're right. It does look correct using Adobe's reader.
I was trying to minimize the programs I had installed on this computer since I never seem to uninstall anything until I'm out of disk space, but I guess I'll need to keep Acrobat Reader.

MagPi Issue #45
Page 46
Diagram in the top left shows a black wire connected to ground on the Pi connected to the breadboard power rail. The other black wire that connects to the power rail on the right is not connected to the same ground rail.
Circuit won't work.

Last edited by scotty101 on Fri Apr 29, 2016 8:44 am, edited 1 time in total.

Issue 46 Page 32 Internet Radio, schematic I believe should show MCP3008 pins VDD and V_REF connected together. Without this mod the output from CH0 does not vary. Also the maximum output appears to be around 0.48, so I have changed the test on line 16 of the program to >= 0.4, and on line 19 to <0.4.

Unfortunately the Radio OP does not start until the program is closed, so will continue to work on it, but hope these two tips are helpful.

I have just followed the USB setup procedure that was published in the Magpi issue 50. I am quite sure that I followed all of the instructions, however, wen I remove the SD card and start up nothing happens. If I start up with the SD card inserted the Pi works properly but keeps polling the USB hard drive. Has any body got an idea what might have gone wrong? I suppose it's quit obvious that I'm a newbie at this and Linux is a mystery to me.

Johnd2117 wrote:I have just followed the USB setup procedure that was published in the Magpi issue 50. I am quite sure that I followed all of the instructions, however, wen I remove the SD card and start up nothing happens. If I start up with the SD card inserted the Pi works properly but keeps polling the USB hard drive. Has any body got an idea what might have gone wrong? I suppose it's quit obvious that I'm a newbie at this and Linux is a mystery to me.

This declares a variable which is not used in this example - this line should be omitted.

Apologies to anyone inconvenienced by these - I did think I had run all the code examples in the book before it was published, but I seem to have missed these. I've double-checked all the rest of the code examples today, and I think all the rest are ok.

Last edited by spl23 on Tue Nov 29, 2016 5:32 pm, edited 1 time in total.

Johnd2117 wrote:I have just followed the USB setup procedure that was published in the Magpi issue 50. I am quite sure that I followed all of the instructions, however, wen I remove the SD card and start up nothing happens. If I start up with the SD card inserted the Pi works properly but keeps polling the USB hard drive. Has any body got an idea what might have gone wrong? I suppose it's quit obvious that I'm a newbie at this and Linux is a mystery to me.

Nothing happens after the two reports, with all three drive I get the colour screen, the report and then nothing. As I said, I can't believe that three drives have the same fault so is it my RPi3 or the code?

In MagPi Essentials - Learning to Code With C by Simon Long, main function keeps being definded as returning void.

As the C standard specifies the return type of main should be int and particularly since the return value of main can be and often is used to signify an error to the caller of the program, who may or may not have been human, would it not make sense to teach the correct return type in a beginner's book?

As the C standard specifies the return type of main should be int and particularly since the return value of main can be and often is used to signify an error to the caller of the program, who may or may not have been human, would it not make sense to teach the correct return type in a beginner's book?

See the second half of chapter 9, where I explain about arguments and return values from main.